Survival and morality differ, in my mind.

Whose survival are we talking about? I'll warn you - "people are basically good" is a fundamental tenet of my life, and one that I have arrived at through extensive research and deep introspection. It informs most everything I do. Just letting you know - don't bring a knife to a gunfight. I can tangle on this one.

Individual survival doesn't much matter because, genetically speaking, selfish individuals remove themselves from the gene pool automagically. This extends on down to paramecia - don't breed, don't matter. Further, one of the most compelling reasons for human survival is "grandparents" - the act of caring for your progeny's progeny. You could still argue that's "selfish" but then I'd pull out The Ultimatum Game and demonstrate that humans "punish" unfair treatment even when they harm their own results in doing so. For that matter, so do macaques. So societal egalitarianism isn't even unique to humans - it's common in primates. So:

In fact, I'm not sure I buy it, or the "well, we're here, so we must be doing something right" reasoning behind it.

That's because you don't know enough about it. Locke didn't invent the social contract, he codified it. "Every man for himself" is not now, has not been and never shall be how societies function. "Social Darwinism" only applies when "survival of the fittest" extends to clans, rather than individuals. Which is not the same thing as families - humans and most primates organize based on a structure that is macroscopically beneficial at an individually-punitive level.

This is especially noticeable in the event of a disaster, like the one in the Philippines, where formerly good, upstanding people are resorting to stealing and violence just to get by.

Where society has, ipso facto, broken down. The immediate response from any corner with surviving society is to clamp down on the lawlessness and provide for the indigent. No one is saying "people never fight." The argument is that the natural state of humanity is one of cooperation. Cherry picking unnatural states that are acknowledged on all sides to be abnormal does not defeat this argument.

The people who are surviving the best over there, right now, are the ones most willing and/or able (via desperation) to commit immoral acts.

A bald assertion with no supporting evidence wholly outside of the argument at hand. Not only is your statement unverifiable, it's irrelevant to the discussion and primarily serves to illustrate your unfounded pessimism.

something about the road to hell and good intentions.

Platitudes are not argument. Don't waste my time.